P. Bolla

Repeatability of milk clotting aptitude evaluated by lactodynamographic analysis

Lactodynamographic analysis is commonly employed to evaluate the clotting aptitude of milk (Frentz, 1965; Tarodo de la Fuente et al. 1969). The individual lactodynamographic response can therefore be used in selection as a quantitative trait. The aim of this work was to estimate either the biological repeatability of the lactodynamographic response or the repeatability of the analytical method itself.

The hairless (hr) gene is involved in the congenital hypotrichosis of Valle del Belice sheep

Congenital hypotrichosis in mammalian species consists of partial or complete absence of hair at birth. The hairless gene is often responsible for this disorder in men, mice and rats. Recent experimental data on Valle del Belice sheep reared in Sicily for milk production, support the genetic control of the ovine hypotrichosis as a Mendelian recessive trait. The ovine hairless gene was chosen as the candidate gene involved in this disorder. Blood samples were collected from Valle del Belice sheep with the normal and hypotrichotic phenotypes. Almost the entire hairless gene was successfully amplified using the long PCR technique. Unrelated sheep with differing phenotypes were randomly chosen for sequencing the amplified products. Different mutations related to the hypotrichotic phenotype were found in exon 3. In fact, sequencing revealed an A/T transversion at position 739, a G/A transition at position 823, and a C/T transition at position 1312. From these nucleotide exchanges, three substitutions of the processed mature protein were deduced at the amino acid positions 247 (Thr/Ser), 275 (Ala/Thr), and 438 (Gln/Stop). A PCR-SSCP based test was developed in order to detect the last mutation, which is responsible for the hypotrichotic phenotype.

Variability of reduced glutathione levels in Massese ewes and its effect on daily milk production.

The variability of the erythrocyte concentration of the tripeptide glutathione was studied in four flocks of Massese sheep. A relationship was found between glutathione level and stage of lactation in which the second month showed the lowest content. Genotype at transferrin and haemoglobin loci was associated with glutathione levels. Homozygotes at the transferrin locus yielded higher levels, while the D allele at the same locus was associated with lower concentrations. Animals with haemoglobin AA showed higher contents of glutathione. Also, a negative correlation was found between daily milk production and glutathione level.

Genetic variability of the ovine αs1-casein

Riassunto Variabilità genetica dell’αs1-caseina ovina. La variabilità genetica dell’ αs1-caseina ovina è stata valuta con particolare attenzione alla presenza delle varianti A, C, e D e del polimorfismo nell’esone 17 che determina una transizione T →C a cui corrisponde la sostituzione aminoacidica Ile186 →Thr186. La variante C è stata suddivisa in due tipi, C’ e C’’, in base all’aminoacido presente in posizione 186. L’aplotipo ancestrale è C’ (Pro13-Ser68-Thr186) mentre C’’ (Pro13-Ser68-Ile186) è risultato il più frequente in 5 razze ovine italiane.

Casein genetic polymorphisms in goat breeds of Lombardy

Riassunto Polimorfismo genetico delle caseine in razze caprine allevate in Lombardia. E’ stato condotto uno studio della variabilità genetica delle caseine in sei razze caprine allevate in Lombardia. La tipizzazione, condotta a livello proteico mediante isoelettrofocalizzazione, è preliminare ad un approccio molecolare dettagliato su un numero più limitato di soggetti, scelti in base a particolari fenotipi caseinici.